I have a couple of ideas. I found some assets on itch for PS1 type games so an original doom parody was one of my ideas. For that I was thinking the metallic theme. Another idea was a strategy game where you place different kinds of units like tanks soldiers and other military types for this I thought your paper or wooden themes. And the last idea was a futuristic rouge-like using pixel art. This one I think should be the hologram theme.